[PATCH v4 0/6] block/md/dm: set chunk_sectors from stacked dev stripe size

[John Garry <john.g.garry@oracle.com>]

This value in io_min is used to configure any atomic write limit for the
stacked device. The idea is that the atomic write unit max is a
power-of-2 factor of the stripe size, and the stripe size is available
in io_min.

Using io_min causes issues, as:
a. it may be mutated
b. the check for io_min being set for determining if we are dealing with
a striped device is hard to get right, as reported in [0].

This series now sets chunk_sectors limit to share stripe size.

[0] https://lore.kernel.org/linux-block/888f3b1d-7817-4007-b3b3-1a2ea04df771@linux.ibm.com/T/#mecca17129f72811137d3c2f1e477634e77f06781

Based on 73d9cb37478f (block/for-6.17/block) block: remove pktcdvd driver

This series fixes issues for v6.16, but it's prob better to have this in
v6.17 at this stage.

Differences to v3:
- relocate max_pow_of_two_factor() to common header and rework (Mikulas)
- cater for overflow from chunk sectors (Mikulas)

Differences to v2:
- Add RB tags (thanks!)

Differences to RFC:
- sanitize chunk_sectors for atomic write limits
- set chunk_sectors in stripe_io_hints()

John Garry (6):
  ilog2: add max_pow_of_two_factor()
  block: sanitize chunk_sectors for atomic write limits
  md/raid0: set chunk_sectors limit
  md/raid10: set chunk_sectors limit
  dm-stripe: limit chunk_sectors to the stripe size
  block: use chunk_sectors when evaluating stacked atomic write limits

 block/blk-settings.c   | 66 +++++++++++++++++++++++++++---------------
 drivers/md/dm-stripe.c |  1 +
 drivers/md/raid0.c     |  1 +
 drivers/md/raid10.c    |  1 +
 fs/xfs/xfs_mount.c     |  5 ----
 include/linux/log2.h   | 14 +++++++++
 6 files changed, 60 insertions(+), 28 deletions(-)

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2.43.5